The vehicle equipped with the fuel cell system is configured to generate electric power with a fuel gas and an oxygen-containing gas respectively supplied to an anode and a cathode of a fuel cell and uses the generated electric power as a driving force. The power generation of the fuel cell produces water on the cathode, accompanied with the electrochemical reaction of hydrogen contained in the fuel gas, for example, hydrogen gas with oxygen contained in the oxygen-containing gas, for example, the air. An electrolyte membrane of the fuel cell generally has the favorable proton conductivity in an adequate wet state. A variety of methods have been proposed to use the produced water on the cathode for humidification of the electrolyte membrane (for example, Patent Literature 1).